A technology of integrating a metal alloy material and a resin material, which are heterogeneous materials, using an adhesive, has been used in many fields such as automobile, electronic products, industrial machines, and the like. However, using the adhesive has disadvantages of difficulty in performing precise bonding, long curing time, and difficulty in maintaining and managing a state of the adhesive.
Due to the above-mentioned reasons, methods of bonding the metal alloy material and the resin material which are heterogeneous materials, without using the adhesive, have been researched in the related art. As one of the methods, a nano method has been actively researched in recent years.
A bonding technology of the heterogeneous materials by the nano method is to form a nano-sized groove on a surface of the metal alloy material and insert the resin material into the groove, which has high tensile force as compared to the case of using the adhesive.
However, when being exposed under harsh conditions, bonding strength of the metal-resin complex is not sufficient, such that a metal-resin complex having more excellent bonding strength has been demanded to be developed.